There is a girl on Flickr, Destini,who makes a lot of baby shower cookies. They look awesome! I finally discovered her trick, a cookie cutter texture set. I got mine as a Christmas present from Country Kitchen Sweetart. My first opportunity to use them was the birth of my niece.
Basically you make a cutout cookie as normal. Then you roll out some fondant, use and impression mat to create the texture, then use the same cookie cutter to cut out the shape. Using a hot glue gun, I created the "J" on some waxed paper. I placed the "J" under the impression mat before rolling over it. It worked pretty well. After baking the cookies, lay the fondant cutout on the cookie. Destini places her fondant on the cookies while they are still warm. The instructions say to cool the cookies and then use a light coating of buttercream to attach the cookies.
I made my fondant cutouts the night before baking and wrapped them in plastic wrap. The wrap unfortunately gave the fondant little crinkles, but since I was making onesies, I guess it gave them a more realistic look. I enjoyed using the texture mats, but it did take a couple tries to get used to using them.